1. Field of the Invention
The present invention relates to a treatment liquid for treating a recording medium, and to an image forming method and image forming apparatus, which use the treatment liquid.
2. Description of the Related Art
Conventionally, when recording is performed on a recording medium using an aqueous recording ink, a surface of the recording medium has been treated with a treatment liquid, followed by recording with the aqueous recording ink, in order to improve fixing ability of an image.
For example, it is disclosed that printing is performed on a recording medium using an ink set containing, in combination, an aqueous ink composition composed of at least a colorant, an anionic resin emulsion, and a water-soluble organic solvent, and water, and a reaction liquid containing a reactant, which forms aggregations as it is brought into contact with the aqueous ink composition, and a cationic resin emulsion, to thereby print an image without color blurring or color breeding on the recording medium (see Japanese Patent Application Laid-Open (JP-A) No. 2010-030305).
In accordance with this method, high quality image formation is achieved by a reaction between the anionic resin emulsion in the ink and the cationic resin emulsion in the reaction liquid. Particularly in the case where a recording medium of low absorbency, such as coated paper, is used, however, a problem is caused in fixing of the ink, as the recording medium is transported at high speed, such as in a line engine system.
When a combination of a conventional treatment liquid containing a cationic resin, and an ink composition containing a colorant encapsulated with a carboxyl group-containing resin is used, the pigment is aggregated on the recording medium due to the cationic resin and the carboxyl group, and therefore an image of high density and high quality can be obtained. However, on the other hand, the force for fixing the aggregated colorant is weak, and therefore transfer smears, such as smearing to a convey roller, are often caused especially when a recording medium is conveyed at high speed, such as in a ling engine system. Moreover, it is often a case that a counter ion in a typical cationic resin is chlorine, which may accelerate corrosion of a device for use.